Using a biscuit cutter, cut a hole into each slice of bread.
Melt the butter in a non-toxic non stick pan over a medium-low heat, about 1 minute.
Egg in a Hole: Add the bread slices. Crack an egg into each bread slice and increase the heat to medium. Cook the eggs for about 3 minutes, until set. If you like a firm white, cover the pan with a lid.
While the egg is cooking, cut the avocado lengthwise with a long sharp knife. Give it a twist and then using the same knife, whack the seed. Turn the seed using the knife to dislodge it.
Scoop out the fruit of the avocado into a small bowl and mash it.
Avocado Toast: When the egg in a hole (also known as bullseye eggs or egg in a basket) is ready, divide the mashed avocado between the two pieces of bread, spreading the avocado onto the toast but not the egg.
Salt and pepper to your liking and enjoy!